1. Field of the Invention
The present invention relates to an inkjet printer, and particularly, to an inkjet printer capable of checking whether a head nozzle is normal, and a method thereof.
2. Description of the Related Art
A printer is now considered as an indispensable peripheral device for a PC user. The popularity of the printer is primarily due to an emergence of an inkjet color printer of a low price.
Generally, an inkjet printer is configured such that ink is ejected on a paper through a fine nozzle provided to a printing head. Here, among various methods of ejecting ink through the nozzle, a method of heating the nozzle of the printing head is most widely used. In this method, the printing head includes a heat resistance RH heating the nozzle, and a driving unit M1 supplying a driving power Vf to the heat resistance RH in responsive to an address input signal. Hereinafter, the heat resistance RH and the driving unit M1 are commonly called a nozzle driving unit. Although one single driving unit M1 and one single heat resistance RH are shown in the drawings, a plurality of nozzles are provided in the printing head, and the nozzle driving unit shown in FIG. 1 is arranged on every nozzle.
In the meantime, dpi (dot per inch) represents a resolution of a printed image and is used as one of standards for measuring a printer performance. More specifically, dpi is a numerical value meaning how many dots are arranged within one inch. For example, 600 dpi means there are six hundred dots within one inch. A comparison between printing results for 360 dpi and 720 dpi shows that the printing results (printed images) are quite different in their dot densities.
In the inkjet printer mentioned above, there occurs a case in which a dot is not formed properly on a printing medium due to a driving unit failure or an ink stoppage of the nozzle. In a case that the dot is not properly formed or considered not properly formed, a user comes to check the result again and again by a spitting method. Malfunction due to the nozzle stoppage like the above case, could be repaired through the spitting method, but in a case of a problem in a nozzle driving circuit, unnecessary consumption of ink is caused. That is, the user is not able to know exactly whether the improper formation of the dot is due to the nozzle stoppage or due to a nozzle driving circuit failure.